feat: multiple parallel workers (#8)

src/lib/engine/stockfish11.ts

@@ -1,12 +1,12 @@
 import { EngineName } from "@/types/enums";
 import { UciEngine } from "./uciEngine";
-import { getEngineWorker } from "./worker";
+import { getEngineWorkers } from "./worker";
 
 export class Stockfish11 {
   public static async create(): Promise<UciEngine> {
-    const worker = getEngineWorker("engines/stockfish-11.js");
+    const workers = getEngineWorkers("engines/stockfish-11.js");
 
-    return UciEngine.create(EngineName.Stockfish11, worker);
+    return UciEngine.create(EngineName.Stockfish11, workers);
   }
 
   public static isSupported() {

src/lib/engine/stockfish16.ts

@@ -1,7 +1,7 @@
 import { EngineName } from "@/types/enums";
 import { UciEngine } from "./uciEngine";
 import { isMultiThreadSupported, isWasmSupported } from "./shared";
-import { getEngineWorker } from "./worker";
+import { getEngineWorkers } from "./worker";
 
 export class Stockfish16 {
   public static async create(nnue?: boolean): Promise<UciEngine> {
@@ -25,9 +25,9 @@ export class Stockfish16 {
       );
     };
 
-    const worker = getEngineWorker(enginePath);
+    const workers = getEngineWorkers(enginePath);
 
-    return UciEngine.create(EngineName.Stockfish16, worker, customEngineInit);
+    return UciEngine.create(EngineName.Stockfish16, workers, customEngineInit);
   }
 
   public static isSupported() {

src/lib/engine/stockfish16_1.ts

@@ -1,7 +1,7 @@
 import { EngineName } from "@/types/enums";
 import { UciEngine } from "./uciEngine";
 import { isMultiThreadSupported, isWasmSupported } from "./shared";
-import { getEngineWorker } from "./worker";
+import { getEngineWorkers } from "./worker";
 
 export class Stockfish16_1 {
   public static async create(lite?: boolean): Promise<UciEngine> {
@@ -20,9 +20,9 @@ export class Stockfish16_1 {
       ? EngineName.Stockfish16_1Lite
       : EngineName.Stockfish16_1;
 
-    const worker = getEngineWorker(enginePath);
+    const workers = getEngineWorkers(enginePath);
 
-    return UciEngine.create(engineName, worker);
+    return UciEngine.create(engineName, workers);
   }
 
   public static isSupported() {

src/lib/engine/stockfish17.ts

@@ -1,7 +1,7 @@
 import { EngineName } from "@/types/enums";
 import { UciEngine } from "./uciEngine";
 import { isMultiThreadSupported, isWasmSupported } from "./shared";
-import { getEngineWorker } from "./worker";
+import { getEngineWorkers } from "./worker";
 
 export class Stockfish17 {
   public static async create(lite?: boolean): Promise<UciEngine> {
@@ -20,9 +20,9 @@ export class Stockfish17 {
       ? EngineName.Stockfish17Lite
       : EngineName.Stockfish17;
 
-    const worker = getEngineWorker(enginePath);
+    const workers = getEngineWorkers(enginePath);
 
-    return UciEngine.create(engineName, worker);
+    return UciEngine.create(engineName, workers);
   }
 
   public static isSupported() {

src/lib/engine/uciEngine.ts

@@ -15,28 +15,38 @@ import { getLichessEval } from "../lichess";
 import { getMovesClassification } from "./helpers/moveClassification";
 import { EngineWorker } from "@/types/engine";
 
+type WorkerJob = {
+  commands: string[];
+  finalMessage: string;
+  onNewMessage?: (messages: string[]) => void;
+  resolve: (messages: string[]) => void;
+};
+
 export class UciEngine {
-  private worker: EngineWorker;
+  private workers: EngineWorker[];
+  private isBusy: boolean[] = [];
+  private workerQueue: WorkerJob[] = [];
   private ready = false;
   private engineName: EngineName;
   private multiPv = 3;
   private skillLevel: number | undefined = undefined;
 
-  private constructor(engineName: EngineName, worker: EngineWorker) {
+  private constructor(engineName: EngineName, workers: EngineWorker[]) {
     this.engineName = engineName;
-    this.worker = worker;
+    this.workers = workers;
+    this.isBusy = new Array(workers.length).fill(false);
   }
 
   public static async create(
     engineName: EngineName,
-    worker: EngineWorker,
+    workers: EngineWorker[],
     customEngineInit?: (
       sendCommands: UciEngine["sendCommands"]
     ) => Promise<void>
   ): Promise<UciEngine> {
-    const engine = new UciEngine(engineName, worker);
+    const engine = new UciEngine(engineName, workers);
 
-    await engine.sendCommands(["uci"], "uciok");
+    await engine.broadcastCommands(["uci"], "uciok");
     await engine.setMultiPv(engine.multiPv, true);
     await customEngineInit?.(engine.sendCommands.bind(engine));
     engine.ready = true;
@@ -45,6 +55,30 @@ export class UciEngine {
     return engine;
   }
 
+  private acquireWorker(): { index: number; worker: EngineWorker } | undefined {
+    for (let i = 0; i < this.workers.length; i++) {
+      if (!this.isBusy[i]) {
+        this.isBusy[i] = true;
+        return { index: i, worker: this.workers[i] };
+      }
+    }
+
+    return undefined;
+  }
+
+  private releaseWorker(index: number) {
+    this.isBusy[index] = false;
+
+    if (this.workerQueue.length > 0) {
+      const nextJob = this.workerQueue.shift()!;
+      this.sendCommands(
+        nextJob.commands,
+        nextJob.finalMessage,
+        nextJob.onNewMessage
+      ).then(nextJob.resolve);
+    }
+  }
+
   private async setMultiPv(multiPv: number, initCase = false) {
     if (!initCase) {
       if (multiPv === this.multiPv) return;
@@ -56,7 +90,7 @@ export class UciEngine {
       throw new Error(`Invalid MultiPV value : ${multiPv}`);
     }
 
-    await this.sendCommands(
+    await this.broadcastCommands(
       [`setoption name MultiPV value ${multiPv}`, "isready"],
       "readyok"
     );
@@ -91,8 +125,15 @@ export class UciEngine {
 
   public shutdown(): void {
     this.ready = false;
-    this.worker.uci("quit");
-    this.worker.terminate?.();
+
+    for (const worker of this.workers) {
+      worker.uci("quit");
+      worker.terminate?.();
+    }
+
+    this.isBusy = Array(this.workers.length).fill(false);
+    this.workerQueue = [];
+
     console.log(`${this.engineName} shutdown`);
   }
 
@@ -109,24 +150,65 @@ export class UciEngine {
     finalMessage: string,
     onNewMessage?: (messages: string[]) => void
   ): Promise<string[]> {
+    const acquired = this.acquireWorker();
+    if (!acquired) {
+      return new Promise((resolve) => {
+        this.workerQueue.push({
+          commands,
+          finalMessage,
+          onNewMessage,
+          resolve,
+        });
+      });
+    }
     return new Promise((resolve) => {
       const messages: string[] = [];
-
-      this.worker.listen = (data) => {
+      acquired.worker.listen = (data) => {
         messages.push(data);
         onNewMessage?.(messages);
 
         if (data.startsWith(finalMessage)) {
+          this.releaseWorker(acquired.index);
           resolve(messages);
         }
       };
-
       for (const command of commands) {
-        this.worker.uci(command);
+        acquired.worker.uci(command);
       }
     });
   }
 
+  private async sendCommandsToWorker(
+    worker: EngineWorker,
+    commands: string[],
+    finalMessage: string,
+    onNewMessage?: (messages: string[]) => void
+  ): Promise<string[]> {
+    return new Promise((resolve) => {
+      const messages: string[] = [];
+      worker.listen = (data) => {
+        messages.push(data);
+        onNewMessage?.(messages);
+        if (data.startsWith(finalMessage)) {
+          resolve(messages);
+        }
+      };
+      for (const command of commands) {
+        worker.uci(command);
+      }
+    });
+  }
+
+  private broadcastCommands(
+    commands: string[],
+    finalMessage: string,
+    onNewMessage?: (messages: string[]) => void
+  ): Promise<string[]>[] {
+    return this.workers.map((worker) =>
+      this.sendCommandsToWorker(worker, commands, finalMessage, onNewMessage)
+    );
+  }
+
   public async evaluateGame({
     fens,
     uciMoves,
@@ -139,14 +221,24 @@ export class UciEngine {
     await this.setMultiPv(multiPv);
     this.ready = false;
 
-    await this.sendCommands(["ucinewgame", "isready"], "readyok");
-    this.worker.uci("position startpos");
+    await this.sendCommands(
+      ["ucinewgame", "position startpos", "isready"],
+      "readyok"
+    );
 
-    const positions: PositionEval[] = [];
-    for (const fen of fens) {
+    const positions: PositionEval[] = new Array(fens.length);
+    let completed = 0;
+
+    const updateProgress = () => {
+      const progress = completed / fens.length;
+      setEvaluationProgress?.(99 - Math.exp(-4 * progress) * 99);
+    };
+
+    await Promise.all(
+      fens.map(async (fen, i) => {
         const whoIsCheckmated = getWhoIsCheckmated(fen);
         if (whoIsCheckmated) {
-        positions.push({
+          positions[i] = {
             lines: [
               {
                 pv: [],
@@ -155,13 +247,15 @@ export class UciEngine {
                 mate: whoIsCheckmated === "w" ? -1 : 1,
               },
             ],
-        });
-        continue;
+          };
+          completed++;
+          updateProgress();
+          return;
         }
 
         const isStalemate = getIsStalemate(fen);
         if (isStalemate) {
-        positions.push({
+          positions[i] = {
             lines: [
               {
                 pv: [],
@@ -170,16 +264,18 @@ export class UciEngine {
                 cp: 0,
               },
             ],
-        });
-        continue;
+          };
+          completed++;
+          updateProgress();
+          return;
         }
 
         const result = await this.evaluatePosition(fen, depth);
-      positions.push(result);
-      setEvaluationProgress?.(
-        99 - Math.exp(-4 * (fens.indexOf(fen) / fens.length)) * 99
+        positions[i] = result;
+        completed++;
+        updateProgress();
+      })
     );
-    }
 
     const positionsWithClassification = getMovesClassification(
       positions,

src/lib/engine/worker.ts

@@ -1,6 +1,12 @@
 import { EngineWorker } from "@/types/engine";
 
-export const getEngineWorker = (enginePath: string): EngineWorker => {
+export const getEngineWorkers = (enginePath: string): EngineWorker[] => {
+  const engineWorkers: EngineWorker[] = [];
+
+  const instanceCount =
+    navigator.hardwareConcurrency - (navigator.hardwareConcurrency % 2 ? 0 : 1);
+
+  for (let i = 0; i < instanceCount; i++) {
     const worker = new Worker(enginePath);
 
     const engineWorker: EngineWorker = {
@@ -13,5 +19,8 @@ export const getEngineWorker = (enginePath: string): EngineWorker => {
       engineWorker.listen(event.data);
     };
 
-  return engineWorker;
+    engineWorkers.push(engineWorker);
+  }
+
+  return engineWorkers;
 };